1. Field of the Invention
The present invention relates to an audio output apparatus, such as a headphone device and a mobile telephone terminal. The present invention also relates to an audio output method and an audio output processing program configured for use in the above-mentioned apparatus. The present invention still relates to an audio output system composed of a headphone device and an audio output device.
2. Description of the Related Art
For example, in reproducing an audio signal for listening in a portable audio player, a headphone or an earphone is generally used to prevent sound from being leaked outside.
These days, the sound leaked from the headphone worn in cars is presenting a social concern as a so-called noise pollution. This sound leakage out of the headphone often occurs when the listener sets a comparatively high reproduction sound volume to the player for listening.
Proposed to overcome this problem are a technique in which the maximum volume is suppressed on the audio player side and a technique in which the reproduction volume is suppressed by compressor processing or a limiter processing (refer to Japanese Patent No. 3016446 (Japanese Patent Laid-open No. Hei 05-49091), hereinafter referred to as Patent Document 1), for example.